1. Technical Field
The present invention relates to a robot hand that can grip an object.
2. Related Art
According to the progress of robot technologies in recent years, a large number of industrial robots are used in manufacturing sites of industrial products. Recently, practical use of robots in medical and nursing facilities is expected. Root hands for the robots to grip objects need to be capable of gripping objects having various sizes and shapes.
As a system adopted in a robot hand to grip an object, there are known a system for projecting plural finger members equivalent to human fingers from a palm member equivalent to a human palm and rotating the finger members with portions of the bases of the finger members as fulcrums to grip an object (e.g., JP-A-2010-201538) and a system for translating the bases of the finger members to reduce a space between the finger members to thereby grip an object (e.g., JP-A-05-220687).
In the system for rotating the finger members with the bases of the finger members as the fulcrums, according to the size of an object to be gripped, angles of the finger members in contact with the object change. Therefore, the shapes and gripping force of finger members need to be changed according to the object. Therefore, the structure and the control of the robot hand are complicated. In this regard, in the system for translating the bases of the finger members, since the angles of the finger members in contact with an object does not change according to the size of the object, it is possible to simplify the structure and the control of the robot hand.
However, in the robot hand adopting the system for translating the bases of the finger members, it is difficult to apply the robot hand to work for gripping a small object. Reasons for the difficulty are as explained below. First, the work for gripping a small object is usually performed in a narrow work space. For example, in work for picking up small components and assembling the components in predetermined positions, the components to be assembled are often arranged close to one another in a narrow space. Usually, a space for placing the robot hand to pick up the components is limited. Further, when the picked-up components are attached, since the components are small, the components often have to be assembled in a narrow space. In the robot hand adopting the system for translating the bases of the finger members, the palm member is large because the palm member has to support the moving bases of the finger members. As a result, the robot hand is increased in size. This makes it difficult to apply the robot hand to work in a narrow work space.